​Promotion lecture by Fulvio Militello for the title as Adjunct Professor. His current position and affiliation is Head of the Plasma Theory and Modelling Department, Culham Centre for Fusion Energy, Abingdon, United Kingdom.

​Abstract of thesis

Turbulence is a natural phenomenon that has fascinated mankind for centuries, even before the introduction of the scientific method. It is ubiquitous in plasmas, given the large range of instabilities affecting them and their intrinsic nonlinear nature. Understanding plasma turbulence is of critical importance for the development of nuclear fusion reactors, which would give us a clean, safe, compact and virtually limitless source of energy. At the stellar temperatures required to achieve fusion in experimental devices (of the order of 100.000.000° K), all the fuel in the reactor is in an unstable plasma state, which needs to be controlled. Turbulence at the plasma boundary (i.e. in the proximity of the material surfaces of the reactor) has extremely important practical consequences for the exhaust of the energy and the particles towards the solid structures of the machine. It affects the life-time of the components, the way we heat the plasma with radio frequency waves and the how we fuel the machine, just to mention a few important aspects of the problem. In other words, understanding and controlling edge turbulence is instrumental to the design of future machines aimed at delivering fusion energy to the power grid. Boundary turbulence is not just applied physics, it is also a fascinating theoretical problem. It encompasses, among other things, the study of the origin and behavior of large amplitude coherent structures that erupt from the core plasma, the interaction between ionized and neural particles, and the nonlinear balance between fluctuations and profiles. With the underlying theme of why this is relevant for future fusion reactors, this talk will give an overview of current research on experimental and theoretical boundary plasma turbulence and its fascinating behavior.